The 6000 series alloys are the most popular alloys in the aluminum extrusion industry. Regardless of them being used in the extrusion industry for over 60 years, some uncertainties still exist in the selection, processing, and application of these alloys as applied to end use. Since national standards or designation rather than end product properties drive choice of alloy, this can result in inappropriate alloy choice and ineffective processing.
There are 45 active original alloys in the 6000 series, of these 6063 and 6060 have dominated the soft alloy extrusion market, while 6005, 6061, and 6082 have commonly been used in the medium strength extrusion market.
* These five original alloys make up 85% of the aluminum extrusions produced in North America.
* Over 70% of aluminum extrusions are made of 6063 and 6061.
* Smaller portions are the 6060, 6005 and 6082 alloys.
Although many 6000 series alloys are not generally used, some of these alloys are beneficial due to their good combination of properties and extrudability. Examples of alloys in limited use include 6463A for bright finish, 6151 for forging stock, 6008 for transportation, and 6101 for electrical applications.
In accordance with international composition limits* let’s look at the more popular alloys: 6060, 6360, 6063, 6005A, 6061, 6351 and 6082 in regards to content of Magnesium and Silicon. Even as the chemical compositions and properties of 6063, 6060, and 6360 can be the same or similar, they have different designations resulting in a trade-off between mechanical properties and extrudability. These architectural alloys are highly extrudable, but possess modest strength levels. They are excellent choices for complex cross sections and multi-hollow profiles, and suitable for painted and anodized finishes.
The medium strength alloys 6005A, 6061, and AA6082 retain higher strength levels, but extrudability is reduced. The extrudability of an alloy is controlled in large part by the magnesium content, the higher the magnesium level, the more difficult it is to extrude. A comparison of 6063 which requires a minimum of 0.45 wt% magnesium, and 6360 which utilizes lower magnesium content makes it more extrudable while still providing the same T5 or T6 minimum mechanical properties and a better surface finish. These alloys are widely used in structural applications due to their combined strength, toughness and resistance to impact.
The versatility of the 6000 series alloys makes them the most popular in North America for extruded products. They exhibit high extrudability, and processing conditions, have moderate strength and good finishing qualities. To obtain the most efficient use of alloys, selection needs to be based on end-user properties allowing the extruder to optimize the alloy selection and processing conditions to the benefit of his operation.
*International Alloy Designations and Chemical Composition Limits for Wrought Aluminum Alloys, 2009